Clarify the use of 0-RTT with DoH (folbricht#408)

doc/configuration.md

@@ -1553,7 +1553,7 @@ Example config files: [well-known.toml](../cmd/routedns/example-config/well-know
 ### DNS-over-HTTPS Resolver
 
 DNS resolvers using the HTTPS protocol are configured with `protocol = "doh"`. By default, DoH uses TCP as transport, but it can also be run over QUIC (UDP) by providing the option `transport = "quic"`. DoH supports two HTTP methods, GET and POST. By default RouteDNS uses the POST method, but can be configured to use GET as well using the option `doh = { method = "GET" }`.
-DoH with QUIC supports 0-RTT. The DoH resolver will try to use 0-RTT connection establishment if `transport = "quic"` and `enable-0rtt = true` are configured. When 0-RTT is enabled, the resolver will disregard the configured method and always use GET instead.
+DoH with QUIC supports 0-RTT. The DoH resolver will try to use 0-RTT connection establishment if `transport = "quic"` and `enable-0rtt = true` are configured. When 0-RTT is enabled, the resolver will disregard the configured method and always use GET instead. This means the configured address nees to contain a URL template (with the `{?dns}` part).
 
 Examples:
 
@@ -1578,7 +1578,7 @@ DoH resolver using QUIC transport.
 
 ```toml
 [resolvers.cloudflare-doh-quic]
-address = "https://cloudflare-dns.com/dns-query"
+address = "https://cloudflare-dns.com/dns-query{?dns}"
 protocol = "doh"
 transport = "quic"
 enable-0rtt = true